In an electrophotographic image forming apparatus, there has been known a structure in which elements such as a photosensitive drum and a developing roller as a rotatable member to be used for image formation are integrated into a cartridge mountable to and dismountable from an image forming apparatus main assembly (hereinafter, main assembly of the image forming apparatus).
In a structure in which a cartridge is dismountably mounted in an image forming apparatus, there is also known a structure in which a toner cartridge containing toner (developer) to be consumed with the image formation can be replaced separately from the photosensitive drum and developing roller.
With such a structure, the toner (developer) contained in the toner cartridge is supplied into a developing device including a developing roller and the like through a discharge port. In addition, in order to prevent the toner from leaking to the outside from the discharge port, an opening and closing member such as a shutter for opening and closing the discharge opening is provided.
For example, Japanese Laid-open Patent Application No. H07-199623 discloses a structure in which a shutter is opened by rotating a toner cartridge when a cylindrical toner cartridge (developer supply container) is mounted in the image forming apparatus main assembly.